Heat-conserving device.



C. H. LAND.

HEAT CONSERWNG DEVICE.

APPLICATION man raw. 3, 1915.

1,197,503. I Patented Sept. 5, 1916.

WITNESSES. IIVI/EIVTOR I 4, 4- I 67 2 zxiefiff mzd m A TTOR/VE VS CHARLES HENRY LAN D, 0F DETROIT, MICHIGAN.

HEAT-CONSERVING DEVICE.

Application filed November 3, 1915.

To all whom it may concern:

Be it known that I, OHARLEs H. LAND, a citizen of the United States, and a resident of Detroit, in the county of WVayne and State of Michigan, have invented a certain new and useful Improvement in Heat-Conserving Devices, of which the following is a specification.

My invention relates to improvements in heat-conserving devices and the process of making the same, and it consists in the articles of manufacture hereinafter described and-the steps taken in producing the same.

An object of my invention is to provide highly refractory objects or articles to be used in connection with furnaces which generate a high heat. The type of furnace with which these articles are primarily designed to be used, is that in which the heat originates from combustible substances more especially coal. gas, petroleum or any of its products, and the like.

A further object of my invention is to provide articles of the type described which may be used most effectively for conserving the heat, thereby rendering the running of the furnace comparatively economical.

A further object of my invention is to provide a series of refractory articles which will permit the conduction of the heat to the point desired with relatively great rapidity, but which will prevent the conduction of the heat to other portions of the furnace'such as the outside, thus tending on the one hand to shorten the time of operation and on the other to prevent loss of heat through leakage.

A further object of my invention is to provide a new form or arrangement of refractory material ina furnace which will result in a saving of the heat and in a reduction of the time for a heating operation.

Arfurther object of my invention is to provide a process by means of which the refractory articles or objects may be manufactured.

Other objects and advantages will appear in the following specification, and the novel features of the invention will be particularly pointed out in the appended claims.

My invention is illustrated in the accompanying drawings forming part of this application, in which Figure 1 is a sectional view through one form of the article; Fig. 2 is a similar view through a modified form; Fig. 8 is a similar view through another modified form; Fig.

Specification of Letters Patent.

Patented Sept. 5, 11.916.

Serial No. 59,490.

4 is a face view showing a plurality of the articles joined together; and Fig. 5 is a sect1on through a furnace showing the means by which the heat is conserved.

In operations requiring high temperatures, such as the baking of artificial teeth and the like, trouble is often experienced in conducting the operation without considerable loss of heat, this heat escaping through the walls of the furnace. Attempts have been made to overcome this waste of heat, but these attempts have generally resulted in the use of refractory articles or materials which,'while preventing a large waste of heat, at the same time also prevent the heat from reaching the point at which the heat is to be concentrated quickly, thus prolonging the time of the operation.

The articles which form the subject of the present invention are designed to prevent the waste of heat and also to allow the heat to be concentrated quickly at the point desired. In order to effect this twofold object, it is necessary to use a plurality of refractory materials, someof which are relatively good conductors of heat and others of which are relatively poor conductors of heat.

By experiment I have found that carborundum is one of the most highly refractory materials which have a relatively high heat conductivity. Furthermore, carborundum can stand an exceedingly high temperature with very little expansion or contraction. Likewise, its quality of supporting heavy pressure or weight is marked. On the other hand, fire clay, bauxite, zirconia, and the like are highly refractory, but at the same time they are very poor heat conductors. Zirconia may be cited as one of the refractory materials which has a maximum nonconductivity. This nonconductivity is greater when the material is in the form of a powder, for if it is held together by a binder its property of non-conductivity is reduced. In order to make use of the material in its maximum non-conducting form, I inclose it in a refractory hollow ball, made of carborundum. In Fig. 1 I have shown such a ball in which the carborundum is shown at A, with the zirconia filling B. In

this instance the Zirconia is shown in granulated or powdered form.

In Fig. 2 I have shown the outer carborundum shell A inclosmg balls of reIractory material having a low heat conductivity, such as zirconia, these balls being designated by C. In making balls, as for instance, that shown in Fig. 1, I may form the core of zirconia held together by a binder such as a temporary binder of starch and then form the exterior shell of carborundum held together by silicate of soda. Now when the ball is heated, the binder is burned out, the Zirconia falls to pieces as a powder, in which form it has a minimum of heat conductivity. In Fig. 2 the ball C may be either zirconia held by some binder which will not permit its disintegration or other refractory material which will not fall to pieces in high heat.

In Fig. 3 the shell A incloses an air space D, the air itself, as is well understood, being a poor heat conductor. In each of the three instances cited above, it will be seen that I have provided a highly refractory shell which is a relatively good conductor of heat with a highly refractory non-heat conducting interior.

In Fig. 4: I have shown the balls thus formed as being connected for a purpose best understood in the consideration of Fig. 5. In this figure, the walls of the furnace are shown at E, the burner at F. The heating chamber G contains a crucible H, and the walls E of the furnace are of course made of refractory material, but even then a good deal of the heat will escape through the walls unless devices such as form the subj ect of the present invention are used to prevent it. The object of course, is to keep the heat concentrated on the crucible. To this end, I place balls of low heat conducting power but of highly refractory material, such as zirconia, immediately next to the inner side of the walls E of the furnace, while on that side next to the crucible II, I place balls of the type already described,z'. e.,having outer conducting shells with an inner non-conducting filling. If the balls were left free, they would not properly support the crucible, but in order to support the crucible and to prevent movement thereof during the firing operation, I prefer to join certain of the balls together in the manner shown in Fig. 4, by suitable joining means K which may be carborundum or other highly refractory material. When the balls are assembled as shown in Fig. 5, the following results are attained: In the first place the crucible is held steady; then when the burner is put in operation, the heat will be quickly conducted by the conducting shells of the balls to the outer surface of the crucible, but it will not be quickly conducted to the inner surfaces of the walls E because of the fact of the non-conductivity of the balls 6. Thefact that all the balls have cores or inner portions of highly refractory material of low conductivity tends to hold back the heat from escaping toward the walls and to concentrate it on the crucible.

Were it not for the outer shell of comparatively high conductivity, the time to heat the crucible would be much longer than it is under the present arrangement, so that it may be seen that I have secured two advantages, a gain in time in the heating operation, and also the conservation of the heat and its concentration upon the crucible. In actual practice, I have used a furnace which was heated almost to the point at which platinum melts, while the exterior of the furnace could be safely handled by the bare hands without any danger of injury to the hands. This is rendered possible by the use of refractory materials, such as I have described.

I am aware that it is not broadly new to use refractory material to hold the heat in a furnace, and I do not claim such as my invention. My invention lies rather in the provision of a furnace having an arrangement for retaining the heat and at the same time for heating the objects quickly, thus hastening the heating operation and also in the refractory articles which permit this action. I may also use solid balls, certain of these solid balls being of refractory conducting material, such as carbid of silicon, the others being of refractory material but being non-conductors of heat, like zirconia. The use of these two sets of refractory balls with the conducting balls nearer the crucible, and the non-conducting balls near the walls of the furnace, will serve to concen trate the heat on the crucible.

I claim 1. A furnace having a heating chamber arranged to receive an object to be heated,

and a plurality of refractory articles dis-.

posed around the object to be heated, within the chamber, certain of said refractory articles having low heat conductivity and others having a portion having 'high heat conductivity.

2. A furnace having a heating chamber adapted to receive an object to be heated, a plurality of highly refractory members disposed within the chamber and surrounding the object to be heated, those members in contact with the inner walls of the furnace having relatively low heat conductivity and those in contact with the object having portions of relatively high heat conductivity, whereby the object is quickly heated.

3. In a furnace, a heating chamber adapted to receive an object to be heated, a plurality of highly refractory members disposed within the chamber and arranged to engage the walls of the furnace and the exterior of the article to be heated, those memrior portions of the last named members conserving and conducting ball comprising having relativelv 10W conductivity. an exterior shell of carborundum, and an 1J 4. As an article (of manulfalcture, a heat interior filling of zirconia. conservin and con uctinv al com risin 5 an exterior shell of carb runclum, sud ail CHARLES HENRY LAND interior filling of a highlv refractory mate- Witnesses: rial with a relatively lOW heat conductivity. ANNA WoNNAcoTT, 5. As an article of manufacture, a heat HAROLD F. COYLE.

Copies of this patent may be obtained for five cents each, by addressing the Commissioner of Patents,

Washington, D. G. 

